1. Field of the Invention
The present invention relates to a capsule endoscope and a capsule endoscope system configured to be introduced into a subject and be able to acquire in-vivo information.
2. Description of the Related Art
Endoscopes in a medical field are conventionally used for in-vivo observation or the like. As one such endoscope, a capsule endoscope has been proposed in recent years which is disposed in a body cavity when swallowed by a subject, picks up images of the subject while moving through the body cavity along with a peristaltic movement, and can wirelessly send picked-up images of the subject to outside as image pickup signals.
Such a capsule endoscope, in general, often photographs two frames per second. Photographing of two frames per second is set because the capsule endoscope is retained in the body cavity for a considerably long period of time, while the capacity of a battery incorporated in the capsule endoscope is limited.
Movement of the capsule endoscope in the body cavity depends on peristaltic movement or the like, and so it is highly probable that the capsule endoscope may be retained in a specific place in the body cavity for a long period of time. On the other hand, since images are periodically picked up even during the retention period, completely identical images may be repeatedly acquired. However, only one frame of these images is sufficient to contribute to diagnosis and other images are wasted.
Therefore, Japanese Patent Application Laid-Open Publication No. 2005-20755 proposes a capsule endoscope configured to compare photographed images with last transmitted images, transmit only photographed images which are substantially different from the last photographed images to an external receiving apparatus to thereby save energy consumed.